2025-06-23_REVISION - M1980244 (96)

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Docusign Envelope ID:45B9721C-FDE2-4821-B686-80BBC79CA6DD With these cross-sections, including the newly added west-to-east cross section through the Elkton Pit, the analysis comprehensively evaluates the most critical stability conditions, confirming the cases • presented are the most conservative possible. 46. Within Section 5.1.1,the subsurface conditions beneath the VLF Expansion were discussed in Section 0.This appears to be a typo, please resubmit this with the correct reference. The reference in the report has been updated to read Section 2.5. 47. Within Section 5.1.1, it states that the"Phreatic conditions within the facility were modeled at approximately 0.5 feet above the LLDPE liner, representing a fully drained VLF with minor accumulation of solution along the base geomembrane." The resulting Factors of Safety presented in Table 5.2 range from 1.2 to 2.2.Also based on the details included in Appendix E which contain the material properties used in the geotechnical evaluation, a consistent unit weight was used for the calculations.The Division interprets the evaluation and material properties to mean that the evaluation was performed to understand the closure or near closure scenario. Please provide a geotechnical evaluation of the VLF Expansion areas taking into consideration the increased slope angle as well as the active application of solution,whereby resulting in an increased unit weight to ensure the slopes achieve the Division's required Factors of Safety during active leaching Operations. The stability models included in Attachment 10 have been updated to take into consideration the active application of solution, resulting in an increased unit weight to ensure the slopes achieve the Division's required Factor of Safety during active leaching operations.An increased slope angle was not modelled as the design VLF Expansion area surfaces are at a 1.4H:1 V slope with benches as shown on Figure 1 in Attachment 10, that represent stacking during operation. 48. Figure 2 contains a scale bar with "Ore Depth" noted however this appears to be a typo as • the Ore surface is depicted. Please update Figure 2. The note has been corrected to read "Ore Surface." 49. Cross Section C on Figure 4 shows a large flat area, approximately 2.2% over 700 feet of liner near the backside of VLF2 Phase 4B. Please discuss measures that will be taken to ensure solution drains from of this area without pooling.As there is a maximum slope grade identified for the facility in the designs, please provide details on if there is a minimum slope specification for the facility.Additionally, please verify the slope arrow and 4.3% grade label listed on Drawing A013 is correct. High Volume Collection Piping is proposed in this area to provide a preferred path for solution to drain and assist in preventing solution from pond in isolated areas. The liner surface grade is variable across the proposed project limits with the primary goal of the surface draining towards the PSSA. The design used the following criteria while developing the proposed liner surface: Minimum grade of 1% and a Maximum Grade of 50%. This criteria is consistent with the existing VLF's. The slope indicator shown on drawing A 13 is correct for location of the label. 50. Figure 2 and Figure 4 depict Cross Section D which passes through VLF1 Phase 6 Stage A and B fully built out and stacked. The sight indicator arrows of Cross Section D on Figure 2 and the depicted Cross Section D on Figure 4 do not match. Please correct orientation/direction of the sight indicator arrows of Cross Section D or how Cross Section D is drawn. The section arrow has been updated. • 51. The lack of historical features located within AM14 expansion areas, especially within the VLF1 Phase 6 area, is concerning. Based on older aerial imagery and the Division's SSR Mining Inc. PAGE 13/19